X-Ray absorbing glass for a color cathode ray tube having a controlled chromaticity value and a selective light absorption

Abstract

A panel glass of a color cathode ray tube exhibiting a high absorption of X-radiation and an excellent resistance to electron and/or X-ray browning, which is modified by 0.1-5.0 wt % Nd 2 0 3 to provide substantially higher relative light transmission in the green and in the red wavelengths of the visible spectrum and a greater selective light absorption in the yellow region of the spectrum, and which is further modified by 0.0005-0.05 wt % Cr 2 O 3 and 0-2 wt % Pr 6 O 11 to control the chromaticity value of the glass to be nearly equal to that of the light emitted from tricolor phosphor P22 and to suppress the dichroism of the glass for different ambient lights. Ingredients of the glass are as follows: 50-75% SiO 2 , 0-5% Al 2 O 3 , 0-4% CaO, 0-3% MgO, 0-13% SrO, 0-16% BaO, 0-3% PbO, O-3% ZnO, 0-4% ZrO 2 , the sum of SrO+BaO+PbO+ZnO+ZrO 2 being 5-25%, 0-4% Li 2 O, 3-15% Na 2 O, 2-15% K 2 O, the sum of Na 2 O+K 2 O being 5-20%, O-2%, TiO 2 , O-3% CeO 2 , 0.1-5.0% Nd 2 O 3 , 0.0005-0.05% Cr 2 O 3 , and 0-2% Pr 6 O 11 .

What is claimed is: 
     
       1. A glass for use in color cathode ray tube having the composition essentially consisting, by weight, of 50-75% SiO 2 , 0-5% Al 2  O 3 , 0-4% CaO, 0-3% MgO, 0-13% SrO, 0-16% BaO, 0-3% PbO, 0-3% ZnO, 0-4% ZrO 2 , the sum of SrO+BaO+PbO+ZnO+ZrO 2   being 5-25%, 0-4% Li 2  O, 3-15% Na 2  O, 2-15% K 2  O, the sum of Na 2  O+K 2  O being 5-20%, 0-2% TiO 2 , 0-3% CeO 2 , 0.1-5.0% Nd 2  O 3 , 0.0005-0.05% Cr 2  O 3 , and 0-2% Pr 6  O 11 . 
     
     
       2. A glass as claimed in claim 1, wherein said composition comprises, by weight, 55-70% SiO 2 , 0.5-4% Al 2  O 3 , 0-3% CaO, 0-2% MgO, 10-23% of SrO+BaO+PbO+ZnO+ZrO 2 , 0-2.5% Li 2  O, 10-19% of Na 2  O+K 2  O, 0-1% TiO 2 , 0.1-1% CeO 2 , 0.3-5% Nd 2  O 3 , 0.0006-0.03% Cr 2  O 3 , and 0-1.5% Pr 6  O 11 . 
     
     
       3. A glass as claimed in claim 1, wherein the amount of said neodium oxide (Nd 2  O 3 ) is 0.3-5% by weight of the glass. 
     
     
       4. A glass as claimed in claim 1, wherein the amount of said chromium oxide is 0.0006-0.03% by weight of the glass. 
     
     
       5. A glass as claimed in claim 1, wherein the amount of said praseodymium oxide is 0-1.5% by weight of the glass.